3) Is there a feature for forgotten passwordYes, if you set your email or security QnA, you can initialize your password when you forgot password.

4) How can I hide pictures and video?If you lock Gallery app then, other user can't see your photo and video.

5) Can't run(find) Smart AppLock(or AppLock disappears in App Drawer)· if you hide Smart AppLock's Icon in options, and then AppLock will disappear. To run it, please put 'Widget' of AppLock in Widget List and click it.